The following are key points to remember from this review of imaging guidance in percutaneous and surgical closure of the left atrial appendage (LAA) and atrial septal defect (ASD):

LAA Closure:

1. Key elements for baseline imaging prior to percutaneous LAA closure include: excluding LAA thrombus, examining LAA anatomy in detail, and measuring LAA orifice and depth. This can be accomplished with both transesophageal echocardiogram (TEE) and cardiac computed tomographic angiography (CCTA). TEE is the traditional modality, widely available, and the gold standard to rule out LAA thrombus. CCTA is noninvasive, has higher spatial resolution, and offers more accurate sizing.
2. Device selection and sizing for percutaneous LAA closure is influenced by LAA shape (“chicken wing” angulation, lobes, trabeculations, and ridges) and size. With 2D TEE in mid-esophageal position, the LAA should be interrogated at 0, 45°, 90°, and 135°. With CCTA, oblique multiplanar reconstructions and 3D volume-rendering reconstructions should be obtained. Adjacent anatomy with regard to proximity of the left upper pulmonary vein, mitral annulus, and pulmonary artery is important. Trajectory of the proximal neck and body of the LAA should be noted.
3. There are specific locations to measure LAA ostium and depth for different devices. Measurements on 2D TEE are done at end-systole at 0°, 45°, 90°, and 135°. Measurements on CCTA are done at late atrial diastole on an oblique view of the LAA ostium where the circumflex artery, left lateral ridge, and LAA are well visualized.
4. 2D/3D TEE guides trans-septal puncture ideally performed in the inferior-posterior portion of the fossa ovalis. It also visualizes correct positon of the guide catheter in the left atrium, monitors device expansion in the LAA, and evaluates the presence and severity of leak around the device. Current criteria to assess size of residual leak are not consistent.
5. Surgical exclusion of the LAA can be performed endocardially or epicardially. When it is performed without cardiopulmonary bypass or myocardial arrest by applying the AtriCure LAA exclusion system, TEE assists with determining that there is a pouch remnant of <5 mm when the clip is in place. When this is performed in conjunction with other open heart procedures, post-procedure TEE assessment prior to terminating bypass can confirm that enough LAA was resected/stapled/ligated and that it does not need to be revised.

ASD Closure:

1. While cardiac catheterization, CT, and cardiac magnetic resonance imaging may provide helpful hemodynamic information and visualization of ASDs, echocardiography remains the primary means of: 1) diagnosing ASD and type of ASD; 2) assessing size of the ASD and adequate rims for device closure; and 3) hemodynamic information regarding shunt, right ventricular dilation and function, and presence/degree of pulmonary hypertension. 3D TEE can provide more accurate information regarding ASD size, shape, and rims.
2. Correct percutaneous device selection for secundum ASD closure is essential in avoiding complications of residual defect, device embolization, and device erosion into surrounding structures. Maximum ASD diameter in “unstretched” (on pre-procedural imaging) and “stretched” (intraprocedural with balloon inflation across the defect) confirmations should be distinguished, as this affects sizing.
3. The six distinct rims (superior vena cava [SVC], aortic, atrioventricular, inferior vena cava [IVC], posteroinferior, and posterosuperior) should be assessed and measured by 3D TEE. For the Amplatzer septal occluder, rims should be ≥5 mm except for the aortic rim, which should be ≥2 mm. For the Amplatzer multi-fenestrated septal occluder, the SVC and aortic rims should be ≥9 mm. Absence of an adequate IVC rim is a contraindication for device closure of ASD, and absence of adequate aortic rim is a major risk factor for device erosion into the aortic root.
4. On 2D TEE, rims can be seen in the following views: 1) mid-esophageal four-chamber view at 0 for atrioventricular and posterosuperior rims; 2) short-axis view at the aortic valve at approximately 60 for aortic and posteroinferior rims; and 3) bi-caval view at approximately 90°-120° for SVC and IVC rims.
5. After device closure of ASD, Doppler imaging should demonstrate complete or near-absence of flow around the device. There may be some flow through the device until it endothelializes. After surgical closure of the ASD, whether primary or with patch, Doppler imaging should show no further shunt across the defect.

Clinical Topics: Cardiac Surgery, Congenital Heart Disease and Pediatric Cardiology, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Pulmonary Hypertension and Venous Thromboembolism, Valvular Heart Disease, Cardiac Surgery and CHD and Pediatrics, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Congenital Heart Disease, CHD and Pediatrics and Imaging, CHD and Pediatrics and Interventions, CHD and Pediatrics and Prevention, Pulmonary Hypertension, Interventions and Imaging, Interventions and Structural Heart Disease, Interventions and Vascular Medicine, Angiography, Computed Tomography, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Nuclear Imaging, Hypertension

Keywords: Atrial Appendage, Atrial Septum, Cardiac Catheterization, Cardiac Surgical Procedures, Cardiopulmonary Bypass, Coronary Angiography, Diagnostic Imaging, Echocardiography, Echocardiography, Doppler, Echocardiography, Transesophageal, Heart Defects, Congenital, Heart Septal Defects, Atrial, Heart Valve Diseases, Hemodynamics, Hypertension, Pulmonary, Magnetic Resonance Imaging, Septal Occluder Device, Systole, Thrombosis, Tomography, X-Ray Computed, Vena Cava, Inferior, Vena Cava, Superior

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